The invention relates to a process for the preparation of an ozonic aqueous solution, optionally in addition to recovering a gas having an elevated ozone content, wherein an aqueous solution is treated in an absorption vessel under pressure with an ozonic gas produced in an ozone generator by silent electrical discharge in air or oxygen and compressed to a pressure of up to 10 bar.
It is known that ozone is an excellent bleaching agent and disinfectant, the ozone preferably having to be available at a relatively high concentration in a gas mixture or in an aqueous solution if applied on a technical scale. Such ozone solutions are needed to an increasing extent, for instance, for bleaching cellulosic materials, for treating drinking water and for oxidizing purposes in the chemical industry.
However, no satisfactory solutions have, so far, been brought to the large-scale preparation of higher concentrated ozonic solutions and gases. This holds, in particular, for the preparation of aqueous solutions having ozone contents of above 200 g O.sub.3 /m.sup.3 water and gases containing more than 160 g O.sub.3 /Nm.sup.3 gas.
When producing ozone by the silent electrical discharge in air, the energy consumption will increase considerably if a high concentration of ozone is to be reached. Therefore, it is sought for reasons of expenditure to operate the ozone generator in the energy-saving range, which, on the other hand, involves an increased use of oxygen, again incurring elevated costs. Attempts have been made to oppose this by recycling into the ozone generator excess oxygen that has not been reacted. To this end, the oxygen must be dry and free of impurities. Purification may, however, involve difficulties if the oxygen contains impurities derived from the reaction of ozone with the medium to be treated. For this reason, processes have been sought to effect the upgrading of ozone in gas, because in such a case the oxygen might be recycled before getting impurified.
According to a known process, it is operated with adsorption masses capable of binding ozone and releasing it later on in high concentrations. The oxygen freed of ozone may be reused. According to another process, ozone is adsorbed from oxygen and then desorbed into a nitrogen atmosphere. None of these processes has been successful in large-scale operation, the problems of a high oxygen consumption or a high energy consumption in the ozonizer still being unsolved.